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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

A 72-hour EC50 value of >118 mg/l and NOEC of >=118 mg/l (mean measured concentration) have been determined for the effects of dimethylsilanediol (CAS 1066-42-8) on growth rate of Pseudokirchnerella subcapitata. 
A 72-hour EC50 value of >100 mg/l and a NOEC of >=100 mg/l (nominal concentration) have been determined for effects of dichloro(methyl)(vinyl)silane (CAS 124-0-9) on growth rate and biomass of Pseudokirchnerella subcapitata. In this test, it is likely that the test organisms were exposed to the hydrolysis products of the read-across substance: methylvinylsilanediol and hydrochloric acid.

Key value for chemical safety assessment

Additional information

No test data for toxicity to aquatic algae and cyanobacteria are available for dimethoxy(methyl)vinylsilane. The hydrolysis half-life of the registration substance indicates that, under conditions relevant to the toxicity to aquatic algae test, hydrolysis to methylvinylsilanediol and methanol will occur (half-life 18.3 minutes at pH 7, 25°C).

Reliable data have been read-across from dimethylsilanediol (CAS 1066-42-8), which is an analogous substance to methylvinylsilandiol, and dichloro(methyl)(vinyl)silane (CAS 124-70-9), which rapidly hydrolyses to the same silanol as the registered substance; methylvinylsilanediol (half-life <1 min at pH 7, 25°C ).

The properties of methanol and the justification of read-across are further discussed in the Ecotoxicological information discussion.

To provide additional evidence that the vinyl side chain does not contribute to toxicity of the registered substance read-across from trimethoxyvinylsilane (CAS 2768-02-7) has been used:

A 7-day EC50 of 210 mg/l and NOEC of ca. 25 mg/l have been determined for the effects of trimethoxyvinylsilane on growth rate of the freshwater algae Pseudokirchnerella subcapitata.